Hi.

NO. No part of the counselling process in illegal. You have interpreted it wrongly. Mop-up round are a last chance at filling vacant seats of various medical institutes. In Mop Round, only a few seats are remaining and majority of the candidates have joined the institute of their choice in prior two rounds. And usually MBBS seats are filled but sometimes due to any circumstances a vacancy is created which is filled by a student who has more priority in the counselling i.e. a student with lower rank. This rank may or may not be equal or higher than the original rank holder of that seat. Thus, according to counselling rules the seat is allotted to the new candidate.

Incase you have a further query, please feel to comment.

Best of Luck